1. Field of the Invention
This invention relates to a linkage for use with a vehicle independent suspension system to indicate the camber angle of a wheel supported by the suspension system.
2. Description of the Prior Art
Vehicle independent suspension systems are presently incorporated in production vehicles such as automobiles, trucks, and vans, etc. Such suspension systems each support an associated wheel and tire for vertical up-and-down movement that is known as suspension jounce. On a horizontal roadway the angle between the center plane of the wheel and a vertical plane that extends through the wheel center point along the direction the wheel rolls is referred to as the wheel camber angle. When the center plane of the wheel is tilted inboard of the vertical plane at the lower side of the wheel, a positive wheel camber angle is present. A negative wheel camber angle is present when the center plane of the wheel is tipped outboard of the vertical plane at the lower side of the wheel. Maximum tire mileage is usually achieved when the wheel camber angle is zero degrees with the center plane of the wheel oriented vertically.
United States production vehicles usually incorporate independent suspension systems only with the front wheels. However, some domestic vehicles do include rear independent suspension systems as well instead of the more conventional solid axle interconnection between the rear wheels. Foreign vehicles conventionally are manufactured with independent suspension systems for both the front and rear wheels.
Foreign and domestic independent suspension systems conventionally incorporate at least one pivotal control arm and a wheel supporting member mounted on the control arm by a joint. If the suspension system is for a front wheel, the wheel supporting member is the steering knuckle on which the wheel is supported. A wheel spindle constitutes the wheel supporting member if the suspension system is for a rear wheel. Usually, a pair of control arms are utilized with domestic independent suspension systems to mount the wheel supporting member. For example, the steering knuckle of a front system is supported on upper and lower control arms by a pair of ball joints. With foreign vehicles, the independent suspension system utilizes a cylinder-like strut that cooperates with a single control arm to mount the wheel supporting member.
Wheel camber angle is conventionally measured by instruments which shine a beam of light from the wheel onto a screen having indications that tell whether the camber angle is proper. The camber angle measurement by these conventional instruments is vehicle attitude sensitive. Normal camber angle change on conventional suspension systems is in the area of one half to one degree of change per inch of suspension travel. Consequently, domestic manufacturers generally specify a vehicle attitude or vehicle loading condition at which the camber angle must be checked or set to a designated amount. Conventional optical measurement equipment requires an accurately leveled base or platform from which to make measurements on the vehicle. The vehicle when placed on the base or platform must be in the correct attitude designated by the manufacturer and is sensitive to tire pressures, wheel run out, fuel and cargo loadings.
If the camber angle is not proper, adjustment is usually accomplished in one of two ways. The mounting of the suspension system on the sprung mass of the vehicle may include accommodations for shims whose thickness determines the camber angle. Thus, a positive or negative camber angle can be changed by adding thicker or thinner shims as required. Another way to adjust the camber angle is to have the components of the suspension system include a suitable threaded or eccentric type of adjustment that changes the camber angle. The following U.S. Pat. Nos. disclose various wheel camber adjustment suspension systems: 2,605,188; 2,664,297; 2,684,253; 2,900,196; 2,923,555; 3,033,588; 3,034,810; and 3,342,507.